Point-Counterpoint: Is An Initial TMA Better Than A Partial Ray Amputation in Patients With Diabetic Neuropathy?

Yes.

Surveying the research and drawing on her own experience, this author says partial ray amputations in this population can lead to complications and further amputation whereas initial TMA procedures can facilitate a durable and functional residual limb.

By Valerie L. Schade, DPM, AACFAS

The primary goal of any limb salvage procedure is to maintain a stable, plantigrade foot that a custom orthotic and extra-depth or custom shoe gear can easily protect. This primary goal serves a secondary outcome of minimizing the potential for future ulceration, infection and amputation.

In the past, the focus has been on saving as much of the foot as possible, taking only the minimum necessary for resolution of the current presentation. This can often lead to one of the most dreaded labels of podiatric surgeons as “whittlers” of the foot. In this era of evidence-based medicine, the reality is that these minimalist efforts often result in a deformed and non-functional foot doomed for repeat incidences of ulceration, infection and amputation.

What The Emerging Research Reveals

Borkosky and Roukis conducted a systematic review of patients with diabetes mellitus and peripheral sensory neuropathy who underwent partial first ray amputation defined as permanent removal of any portion of the osseous structures distal to the medial cuneiform.1 The review excluded patients with critical limb ischemia. A total of five studies (21 percent) met the inclusion criteria. The weighted mean age of the 435 included patients was 59 years. The weighted mean follow-up was 26 months. Results of the systematic review found that one in every five patients required more proximal amputation with the final level being an additional digit (37 percent), transmetatarsal amputation (TMA) (37 percent), below-knee amputation (BKA) (29 percent) and LisFranc amputation (1 percent).

The authors determined that a partial first ray amputation in patients with diabetes and peripheral sensory neuropathy and without vascular compromise may not result in a durable, functional foot.1 They postulated that a well-balanced TMA may be a more predictable level of amputation in regard to durability and longevity.

Taking this data, Borksoky and Roukis performed a retrospective review using the same inclusion and exclusion criteria as described above for analysis of their own facility’s results over an 11-year period.2 A total of 59 patients who had a partial first ray amputation met the inclusion criteria. The mean age was 67 years. The mean follow-up time was 34 months. A total of 69 percent of these patients developed a new ulceration at a mean of 11 months from the index procedure. The mortality rate was 48 percent with death occurring at a mean of 35 months from the index procedure. In addition, 36 percent of patients required an average of two ancillary procedures such as flexor tenotomies and an average of 27 clinical visits from index procedure to the time of definitive treatment defined as complete healing of the index wound or time to reamputation. Ninety-two percent of patients required prolonged postoperative antibiotic therapy with a mean of two different antibiotics prescribed.

Combining their own facility’s data with that from their previously performed systematic review, the authors felt that a partial first ray amputation at any level is neither reliable nor durable.2 The question of whether these patients would be better served by the predictability, durability and longevity of a well-balanced transmetatarsal amputation still existed.

Comparing The Success Rates Of Various Levels Of Amputation

Cohen and colleagues performed a retrospective review of 53 male patients with peripheral neuropathy who had a partial ray resection, panmetatarsal head resection or TMA.3 Thirty-three patients (35 feet) had an isolated ray resection. The average follow-up time was 28 months. The overall success rate was 37 percent. Individual success rates for isolated ray resections were 36 percent for the first ray, 14 percent for the second ray, 17 percent for the third ray, 0 percent for the fourth ray and 78 percent for the fifth ray. The most common complication was transfer ulceration resulting in infection and the need for further amputation. Six patients (a total of seven feet) had panmetatarsal head resection.3 The average follow-up time was 17 months with a success rate of 86 percent.

Fourteen patients (15 feet) had a transmetatarsal amputation. The average follow-up time was 17 months. There were adjunctive procedures in six feet.3 These procedures included Achilles tendon lengthening, anterior tibial tendon transfer to the peroneus tertius tendon, transfer of the extensor hallucis longus tendon to the anterior tibial tendon insertion, transfer of the anterior tibial tendon to the peroneus tertius tendon, and transfer of the extensor hallucis longus to the posterior tibial tendon. Complications occurred in three patients. One patient developed a new ulceration at the distal aspect of the residual foot that required a full thickness advancement flap and Achilles tendon lengthening to heal. One patient had delayed healing and required revision of the residual second metatarsal. Finally, one patient who was discharged with an open plantar flap and lost to follow-up for 14 months ended up with an above-knee amputation. None of these patients had any tendon balancing procedures at the time of their index TMA. Their reported success rate following a TMA was 93 percent.

In the study, more than 60 percent of patients who had an isolated ray resection developed a new or recurrent ulceration more than 24 months following their index procedure.3 Given that, the authors concluded that one should relay these risks to the patient at the initial presentation and stressed the importance of close postoperative monitoring. They felt that a TMA was a more stable and reliable procedure. The authors also stressed the importance of considering adjunctive tendon and osseous balancing procedures to combat the remaining flexible or rigid equinovarus deformity in order to minimize the risk of ulceration, infection and further amputation.

Brown and coworkers compared the morbidity, mortality, requirement of more proximal ipsilateral amputation and functional outcomes among patients who had a BKA, TMA, Chopart amputation, partial calcanectomy and total calcanectomy.4 Patients who had a TMA had a lower rate of mortality in comparison to those who underwent a BKA at one, three and five years postoperative with statistical significance at one and three years. The rate of reamputation following a TMA was 0.09. Of the 21 patients who had a TMA, only two patients (10 percent) required more proximal ipsilateral amputation. One patient had the second amputation at 0.3 years and another patient had it at 4.2 years following the index procedure. The study did not state the reason for re-amputation.

Assessing postoperative ambulatory status with the validated Volpicelli scale, Brown and colleagues found that patients who underwent a TMA remained as unlimited household ambulators.4 The study authors determined that a TMA provided a predictable, durable and functional residual limb.

A Closer Look At The Author’s Experience

My colleague and I performed a retrospective review of patients with peripheral neuropathy who underwent a TMA at our facility over a six-year period.5 The review excluded patients if they required a higher level of amputation secondary to progressive necrosis or infection. A total of 17 patients (17 feet) met all of the inclusion criteria. The mean age was 69 years. The mean follow-up time was four years. All patients had adjunctive tendon balancing procedures consisting of an Achilles tendon lengthening to combat equinus. Each patient also had either a peroneus brevis to peroneus longus tendon transfer, a split tibialis anterior tendon transfer, a flexor hallucis longus transfer, an extensor digitorum longus transfer, a posterior tibial recession or internal hardware to combat varus deformity of the foot.

More than 50 percent of patients admitted to not using a custom insert and/or ambulating barefoot.5 Despite this, only three patients (18 percent) developed an ulceration. One was due to a flexible equinovarus deformity that healed with use of an AFO, one was due to a limb length discrepancy secondary to a chronically infected total hip arthroplasty on the contralateral limb that also healed with the use of an AFO and one was continuing care with another provider and was lost to follow-up. This put our overall success rate at 94 percent, similar to the finding by Cohen and colleagues.3,5

Final Thoughts

Any loss of the foot puts an emotional toll on the patient. The need for perpetual follow-up for prolonged antibiotic therapy, delayed healing, wound recurrence or occurrence, and further amputation can further exacerbate this emotional toll as well as place physical and financial burdens on the patient. Existing evidence demonstrates that an isolated ray resection does not result in a durable and functional foot, and has a poor prognosis for longevity. The future focus needs to be on form and function in the form of a well-balanced TMA to combat residual equinovarus deformity of the foot and away from the minimalist efforts of the past to eradicate infection.

Dr. Schade is the Chief of the Limb Preservation Service at Madigan Army Medical Center in Tacoma, Wash. She is an Associate of the American College of Foot and Ankle Surgeons.

No.

This author says with the proper protocol in place, first ray amputations can provide good long-term healing and functional outcomes.

By Suhad Hadi, DPM, FACFAS

The growing emphasis on limb salvage and multidisciplinary approaches to care has brought on an apparent decline in the number of major lower extremity amputations with a noted increase in the number of foot level amputations.1-4 With the change in prevalence, there is much controversy surrounding decision making in regard to “definitive” foot level amputations.

As we continue to witness a decrease in below-knee level amputations and an increase in partial foot level amputations, the questions surrounding their longevity and benefits come further into play.1 Partial foot amputations in general have been under scrutiny in regard to what we can consider a low success rate of maintained healing regardless of amputation level.

Research has shown that 30 percent of all partial foot level amputations require secondary amputation regardless of the specific levels, a percentage that includes partial first ray amputations and transmetatarsal amputations (TMAs).1 Despite the fact these rates are twice as high as transtibial amputation rates, we continue to recognize the increase in partial foot amputations and the efforts to increase their functionality and longevity.

What The Literature Reveals

There is much literature in support of midfoot level amputations (and the TMA in particular) but there is a noted paucity in regard to more recent outcomes in support of partial ray amputations, specifically those of the first ray.

Many studies have identified the associated risk of more proximal amputation in patients who undergo a partial first ray amputation.1-5 The risk of more proximal amputation ranges from 25 to 40 percent.1-5 In a retrospective review of 30 patients who had a partial first ray amputation, Kadukammakal and colleagues found that nine of these patients (30 percent) had a subsequent TMA at one-year follow-up.4 However, of those 12 patients undergoing a TMA, six had an ischemic component, which would initially be a greater indicator of the potential of more proximal amputation.

Furthermore, Borkosky and Roukis performed a systematic review of studies involving any form of partial first ray amputation in an effort to identify the incidence of re-amputation in patients with diabetic neuropathy.3 They ultimately concluded that one out of every five patients had re-amputation. However, there was no indication — in the form of ischemia, infection or both — as to why further amputation was necessary. Ultimately, this review found only a 19.8 percent re-amputation rate following partial first ray amputation, which was 5 to 20 percent lower than in previous studies.4-6 However, the authors went on to recognize and question the potential for a reduction in numbers if appropriate bracing techniques were in place.3

Being critical of the literature and the emphasis on reported re-amputation rates often leaves one failing to interpret and recognize the success rates ranging from 60 to 80 percent of patients maintaining a successful, functional and healed outcome with a partial first ray amputation.6 Ultimately, one must recognize that the trend in reviewing the outcome studies tends to demonstrate a progressive decline in re-amputation rates with partial first ray amputations. Therefore, it is premature to exclude this procedure from one’s armamentarium in regard to amputation planning.

Often with surgical planning, we consider partial first ray amputations an initial debridement in an effort to eradicate infection, regardless of parameters — such as appropriate infection control and intact vascular status — supporting overall healing at that level. There is always the fear of the lateral transfer of weightbearing forces to the residual foot and subsequent transfer lesions as a consequence of reported forefoot sequelae.2 It is the common progression for amputations at the first ray level to demonstrate lesser digital contractures at the proximal interphalangeal and metatarsophalangeal joints, anterior advancement of the plantar fat pad and subsequent potential for transfer lesions.

These factors and the implied increased risk of re-ulceration and further risk of infection or more proximal amputation often lead surgeons to contemplate a midfoot level amputation in the hopes of a more successful outcome. It is, however, the understanding of these sequelae that should instead reinforce the benefits of implementing further adjunctive surgical planning and prosthetic measures to maximize the long-term outcomes of partial first ray amputations.5,7

A Closer Look At Adjunctive Surgical Options

Cunha and coworkers discussed the role of tendo-Achilles lengthening procedures to further reduce forefoot pressures and prevent re-ulceration or proximal amputation in eight of 12 patients.7 They identified four patients who needed further debridement or progression to a TMA. However, their findings further validate the importance of preoperatively recognizing and addressing deformities that may ultimately compromise the successful outcome of a partial first ray amputation.

Miller and colleagues further discuss the potential role of panmetatarsal head resection procedures in reducing forefoot pressures in an effort to prevent forefoot ulcerations and the potential risk of TMA.5

Recognizing The Benefit Of Post-Op Prosthetic Modifications

The recognition of progressive deformity pre- and post-amputation will allow for a more comprehensive prosthetic prescription that will more effectively sustain the foot at the level of a partial first ray amputation. It would behoove the surgeon to gain thorough knowledge as to the role of prosthetic modifications, individual and in combination, in an effort to achieve the best outcome for the patient.

Amputation filler additions to full-contact accommodative insoles can compensate to various degrees for the loss of the hallux. Modifying shoes to include a carbon plate or rocker-type forefoot will further aid in offloading the forefoot.

It is also crucial to note that the majority of patients who have associated comorbidities such as coronary artery disease, chronic obstructive pulmonary disease or advanced systemic disease will often require the use of assistive devices in gait, such as canes, walkers, etc. This can further facilitate modifications in walking speed to increase overall function in the prescription shoegear. One may also consider the addition of a dynamic ankle foot orthotic (AFO) device similar to that for patients with a transmetatarsal amputation in an effort to reduce some of the forces during gait that may increase forefoot and lateral weightbearing distributions.

Ultimately, clinicians must be thorough in regard to post-procedure prosthetic prescriptions and work closely with prosthetists in an effort to sustain an acceptable functional outcome post partial first ray amputation.

Do Patients With First Ray Amputations Have Greater Function And Mobility Than Those Who Have Had TMAs?

In regard to biomechanical function, it has been widely accepted that a TMA provides a more stable base, a re-established metatarsal parabola and decreased energy expenditure in comparison to partial first ray amputations. However, more recent studies have further questioned these claims.

Dillon and Fatone explain that once the amputation is beyond the metatarsal heads collectively, via transmetatarsal or tarsal level amputations, the respective foot length no longer contributes to power generation at the ankle.1 They also note that the outcome is equivalent to the loss of ankle power that occurs with a transtibial amputation, resulting in further compensation at the hip. Other similarities include walking speeds, which the study found to be comparable in patients with partial foot level amputations and transtibial amputations. This study further questions the increased function or mobility of patients who have had midfoot amputation when taking less than moderate walking speeds into account.

Ultimately, these questions raise the need for further research and open the door to question the superiority in function, mobility and healing rates of a midfoot amputation in comparison to a partial first ray amputation.

How Psychosocial Factors Come Into Play With Amputation

Aside from the goals to attempt to achieve function, mobility and minimal deformity in amputation planning, one must also take into account patient factors such as quality of life and psychosocial considerations. Amputation resulting from prolonged ulcer or wound healing has already taxed the patient and his or her social network. Progression to amputation has the potential to further compromise quality of life.

Patients often fear the “whittling away” effect while at the same time desiring the most minimal amputation level in effort to preserve as much of the structural integrity of the foot. This is at times a mechanism to attempt to better cope psychologically with having the amputation. At times, a partial first ray amputation can fulfill the expectation in the patient to maintain the majority of the foot. If healing parameters are optimal for this level of amputation and one implements appropriate post-amputation prosthetic and activity modifications, a partial first ray amputation can provide an acceptable level of healing and function in the long term.

The importance of function and prevention of progressive deformity are key components to selecting the appropriate amputation level. However, one cannot exclude the role of psychosocial parameters surrounding amputation. One must take into account the toll on both the patient and his or her social network. From the initial onset of ulceration, the compromise in quality of life can impact the successful outcomes in regard to ulcer healing or amputation healing should one become necessary.

The Eurodiale study found that health related quality-of-life factors measured via five domains (mobility, self-care, usual activities, pain/discomfort and anxiety/depression) influenced amputation risk and outcomes.8 Therefore, as noted in the study, we can further speculate that psychosocial and health factors may be necessary additions to the overall limb salvage efforts of the multidisciplinary team.

In Conclusion

It is important to realize that no amputation is without its own inherent risks and appropriately weighing these risks and benefits leads to appropriate amputation level selection. One must tailor procedures accordingly in order to ensure the best outcome for the patient in regard to healing, function and quality of life issues. Appropriate perioperative planning will minimize healing complications and the risk of further amputation.1 The most success with first ray amputation occurs in patients with appropriate control of infection, optimal perioperative parameters in regard to nutrition and total lymphocyte count, optimal vascular status, appropriate implementation of adjunctive surgical management, adherence to postoperative restrictions, and long-term prosthetic fitting.1 Further experience has shown that access to a well-constructed multidisciplinary care team further encourages successful outcomes and patient adherence.

Therefore, there are several key factors that can support successful outcomes of partial first ray amputations. These factors include identifying the structural makeup of the surgical foot; access to comprehensive care; appropriate prosthetic prescriptions; identifying the need for adjunctive surgical interventions; and optimizing nutritional status and infection defenses.

Ultimately, it is important to optimize all factors for healing and recognize the equivocal findings in regard to energy expenditure, biomechanical stresses, progressive deformity and re-amputation risks associated with all foot level amputations. While we have considered transmetatarsal amputations a “more definitive” foot level amputation, they require re-amputation or major amputation in 25 to 30 percent of cases.1,5 This number is not significantly smaller and, in some studies, is equally comparable to the outcomes with partial first ray amputations, making partial first ray amputations difficult to exclude in amputation planning.

Appreciating that regardless of level, there is little difference in the percentage of partial foot amputations that require re-amputation opens the door to better understanding the potential success of a partial first ray amputation.

Dr. Hadi is a faculty member with the Louis Stokes Cleveland Veterans Administration. She is a Fellow of the American College of Foot and Ankle Surgeons.